Elastomeric laminates are used in various products including absorbent articles (e.g., diapers, incontinence articles, feminine hygiene pads), clothing, body wraps, etc. Such laminates typically include an elastomeric layer that provides elasticity to the laminate and an outer layer (referred to herein as a coverstock layer) that is less stretchable but suitable for providing durability and desirable tactile properties. In this way, the laminate permits a component of an article to closely and comfortably contact the wearer while providing desirable exterior qualities.
Elastic laminates can be produced by multiple methods. For example, the laminate may be in the form a gathered laminate, wherein the coverstock layer forms rugosities when the stretchable layer is relaxed. Said gathered laminates may be formed by extending the stretchable material to a greater extent than the coverstock material at the time of lamination. Alternatively, the coverstock material may be corrugated and the elastic material may be in its relaxed state at the time of lamination. In either scenario, following lamination, the coverstock gathers or bunches and forms rugosities when the laminate is in a relaxed state.
Another type of elastomeric laminate is a zero strain laminate. During lamination, the coverstock and elastic layers are joined at approximately zero relative strain (i.e., neither layer is strained to a greater extent than the other layer). Zero strain laminates are activated by a mechanical straining process, which creates separations or deformations in the coverstock materials and renders the laminate elastically extensible.
Known elastomeric materials and laminates have limitations. Elastic materials alone may not provide desirable tactile properties and textures required for the end products in which the materials are incorporated. Further, elastic materials can be expensive and limited in the properties they can provide (e.g., limited in direction of extensibility, limited in ability to provide differential modulus, etc.). Laminates likewise may lack some desired cost efficiency and design versatility. For instance, gathered laminates can be costly to manufacture due to costs of coverstock materials that are necessary to ensure the desired amount of stretch (e.g., if the laminate is to stretch twice its relaxed length, than the coverstock should be twice as long as the elastic material). Moreover, achieving differential properties (e.g., differential modulus) can be challenging and costly as variations in the elastic material forming the stretchable layer would be necessary (e.g., different strain levels, basis weights, formulations). The manufacturing of zero strain laminates also presents challenges. The mechanical straining process may result in damage to one or more layers of the laminate. Indeed, areas of a layer that introduce a variation (e.g., a change in material and/or caliper, a bond site, or an imperfection) may result in added stress in said area, leading to weaknesses or tears in the one or more layers or in the laminate as a whole. Increasing the number of layers undergoing activation results in a greater probability that a defect in one or more locations will occur. Further, in plastically deforming the coverstock material, there is a risk that portions of the material may be completely destroyed. Weaknesses and tears can lead to exposure of the elastic material and/or excess fuzz, both of which could lead to downtime and inefficiencies in manufacturing, result in product performance issues and/or become a comfort and/or safety issue to the end user. In addition, by mechanical straining all layers at once, any defects created will extend through the entire laminate. Prevention of these problems often requires more expensive coverstock materials and/or slower process rates. Known laminates are also limited in the variations in textures, surface patterns and related properties that can be created, particularly where it is desirable to have different textures and patterns on either side of the laminate.
Therefore, there is a continued need to reduce costs and enhance efficiency in creating elastomeric laminates. There is a further need for manufacturing processes that enable differential properties in targeted regions and/or differential properties that can follow targeted pathways in a product. Likewise, it would be beneficial to provide elastomeric laminates with desirable textures on both exterior surfaces and/or that embody different activation patterns on various layers in order to more fully optimize performance.